Knowledge of how the home environment affects children's healthy weight is limited by lack of well-developed, comprehensive measures. The objective of this research is to develop HomeSTEAD, the Home Self- administered Tool for Environmental assessment of Activity and Diet, and provide evidence for the reliability of scores and validity of inferences from this instrument. The proposal comes from a group of highly experienced researchers and will build off of a preliminary home assessment instrument developed by the team. The original instrument was administered via telephone interview and initial testing, though promising, identified areas for improvement. The current project includes three aims. Aim 1 consists of developing candidate items for a self-administered measure of home environmental factors hypothesized to impact diet and physical activity behaviors of children (age 3-12 y). Item selection will draw on data from our preliminary instrument, existing items and/or instruments, published literature, and expert opinion. For Aim 2, we will maximize comprehension of items, terms, and definitions in the newly developed HomeSTEAD using one-on- one guided cognitive interviews in a diverse sample of parents (n=60) to insure that our intention for an item agrees with participant interpretation. For Aim 3, we will examine reliability and validity evidence for the new survey by administering the survey to an ethnically diverse sample of families (n=130) with at least one child age 3-12y. A designated parent will complete the survey three times: Time 1- within 48 hours prior to the in- home observation by research staff (validity);Time 2- concurrent with the in-home observation (reliability);and Time 3 - approximately 10 days later (trait stability, reliability). Traditional estimates of reliability and validity (Kappa, ICC, correlation) will be calculated for each item and absolute agreement across trials evaluated using ANOVA. For items not feasible to observe during the home visit (e.g., policies for TV viewing), reliability and validity will be tested through exploratory and confirmatory factor analysis. Successful completion of this project will result in a reliable and valid self-administered survey that can be used by researchers to quantify aspects of the home environment that may influence weight-related behaviors in children. PUBLIC HEALTH RELEVANCE: The role of the environment in the etiology of child obesity has received increased attention. For children, the home is the most proximate and influential environment, providing the context in which eating and activity habits develop. However, understanding the relationship between home environment and diet, activity, and weight, is impaired by a lack of valid and reliable assessment tools. The proposed HomeSTEAD tool will address this gap and help elucidate the relationship between home and child obesity and plan interventions.